As part of his family's acrobatic circus troupe travelling through the forest, Leo is expected to perform feats of daring on the high wire. After he ruins the final show of the season, Leo decides to run away. With winter fast approaching, Leo is forced to take refuge with a kindly mole couple, whose underground home and unfamiliar life present some difficult challenges. But in learning some new skills, Leo also learns that what makes him different also makes him strong.